problem in non blocking code

This is a discussion on problem in non blocking code within the Networking/Device Communication forums, part of the General Programming Boards category; the code keeps crashing i tried to know whish state it crashes in but didnt know Code: #include "inc.h" void ...

  1. #1
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    problem in non blocking code

    the code keeps crashing i tried to know whish state it crashes in but didnt know
    Code:
    #include "inc.h"
    void connect()
    {
    	u_long iMode = 1;
    	SOCKET SITE;
    	SOCKADDR_IN serverinfo;
    	LPHOSTENT hostEntry;
    	hostEntry = gethostbyname("www.yahoo.com");	// Specifying the server by its name;
    	SITE=socket(AF_INET,//we gonna use internet
    		       SOCK_STREAM,//best effor socks
    			   IPPROTO_UDP);//we gonna use tcp protocol
    	//next is our strctre of stuff   
    
    	serverinfo.sin_family=AF_INET;
    
    	serverinfo.sin_addr = *((LPIN_ADDR)*hostEntry->h_addr_list);
    
    	serverinfo.sin_port=htons(80);
    
    	if(ioctlsocket(SITE,FIONBIO,&iMode)==INVALID_SOCKET)//we begin using our non blocking sockets
    	{
    		MessageBox(NULL,"FUNCTION FAILED","FAILURE",MB_OK);
    		exit(0);
    	}
    	connect(SITE,(SOCKADDR*)&serverinfo,sizeof serverinfo);
    }
    int WINAPI WinMain(IN HINSTANCE hInstance, IN HINSTANCE hPrevInstance, IN LPSTR lpCmdLine, IN int nShowCmd )
    {
    	connect();
    }

  2. #2
    Registered User carrotcake1029's Avatar
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    Uhh, not sure if this is related to your error, but you have created a function (connect) that is already defined in winsock2.h, which I assume you have included.

    Also saw this while glancing over it:
    Code:
     IPPROTO_UDP);//we gonna use tcp protocol
    ya....

    Also since you made your socket nonblocking, you will never even know if you connected as you have nothing to block after you call connect(), your program will just terminate.
    Last edited by carrotcake1029; 03-19-2009 at 10:40 PM.

  3. #3
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    i changed that to tcp but now how can i connect after i got it intilised?

  4. #4
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    also i thought that will just connect it wont like send or recv something ? but program just crash after running

  5. #5
    Registered User carrotcake1029's Avatar
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    Put in some printf's or something to figure out where exactly the code is crashing. Then you will know immediately after which line of code there is a problem, and from there you can diagnose it yourself, or ask if you can't figure it out.

  6. #6
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    Where's the call to WSAStartup()?

    I'm betting that your call to gethostbyname() is returning NULL since you haven't called WSAStartup(). This is causing a crash when you try to do hostEntry->h_addr_list.

  7. #7
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    i did in main thats y before it crashed coz i didnt intilised it before

  8. #8
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    srry 1 more question does recv in non blocking same as blocking i mean it returns smaller or = to zero if it failed ?

  9. #9
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    The return value is the same. Keep in mind that recv will fail if the call would block.

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